PTA.S4.Q20 - all orchid species that are pollinated

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  BinghamtonDave Alum Member ⭐ 🍌🍌

  November 2017 8716 karma

  You're totally correct. The flaw here is the necessary/sufficient confusion, also known as "the oldest trick in the book." What is different here is the wording. This is probably the most abstract way in which the LSAT has described the sufficient/necessary flaw in my view. Yet, even given that abstraction, this is a helpful problem to revisit and go deep into because it gets in my estimation to the heart of what a sufficient/necessary flaw is.

  So to begin with, we are provided the following in the premise:
  in the domain of orchid species, every one pollinated by insects posses features that attract insects.
  We can use this shorthand:
  If pollinated----->have features that attract
  Because this is our premise, we accept this as fact. As a fact about the world in which the author will attempt to draw a conclusion.

  On the basis of that fact, our author creates the following argument:
  We found an example of something that has features (the necessary element in our conditional statement
  therefore
  that example is pollinated
  The argument our author has constructed is:
  Feature that attract------->pollinated

  Lets look at the first half of the answer choice:
  “treats a characteristic known to be true of a particular class of things…” This is referent to the statement given to be true in the first sentence of the stimulus:
  If pollinated———>have features
  The characteristic "known to be true" is "have features." The class of things it is known to be true of is "if pollinated."

  So, in short, we can fill in the referent for answer choice (D) so far as:
  "Treats the fact that have features is necessary for pollinated..."

  This answer choice is saying that the error in the reasoning is that the argument treats the above fact as if
  "That characteristic were unique to that class" (emphasis added is my own)

  Unique here means the first definition listed:
  http://www.dictionary.com/browse/unique?s=t

  The latter part of this answer choices means that we treat the characteristic "have features" as unique to meaning existing solely in conjunction with that class (which is referent to "pollinated.") This is a convoluted way of saying that if we have "features that attract" then on the basis of the uniqueness of that feature's existence within a class, we draw the conclusion: "pollinated." So, to shorten this even further:
  Features that attract----->pollinated

  Ok, so I thought of an example:
  If the bird is a male North American warbler then the bird is yellow
  On the basis of the example of above: what is "known to be true of a particular class of things?
  That if we have a male NA warbler (class) then we have a yellow bird (known to be true.)

  On the basis of that statement about the world I have spotted a yellow bird, therefore I draw the conclusion that: I have spotted a male NA warbler.
  Yellow bird------>Male NA warbler

  I have taken the characteristic (yellow) to be unique to meaning existing solely with "NA male warbler"

  Now, lets think for a minute why this is erroneous. Because if we are given:
  NA male warbler----->yellow bird As a statement about the world
  on the basis of that statement we do not have enough information to draw the conclusion:
  Yellow bird---->NA male warbler

  Because Yellow bird could mean a chickadee. Yellow bird is not sufficient for NA male warblers. The characteristic "yellow bird" is not unique to NA male warblers. Meaning if we see "yellow bird" then due to its existence solely with NA warbler that we say that the characteristic "yellow bird" is sufficient for NA male warbler.

  In summation, I hope this helps. Any further questions do not hesitate to reach out.
  David